<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>isSymbol</title>
</head>

<body>
    <script>
        const isSymbol = val => typeof val === 'symbol';
        document.writeln(`isSymbol(Symbol('x'))的结果是:${isSymbol(Symbol('x'))}`)
    </script>
</body>

</html>